Near Record Sea Ice in Antarctica (again)

The sea ice extent in Antarctica attained a near-record high level of 18.7 million square kilometres in mid-August this year, according to studies by the USA National Snow and Ice Data Center.

Normally averaging 18 million square kilometres at the height of winter, the increase is part of a long-term trend and is paradoxically consistent with how scientists believe global warming may affect the southern ocean around Antarctica. 

Unusually large fields of ice were reported in the Bellingshausen, Amundsen, and Ross seas, and in the western Indian Ocean sector.

Ice extent does vary during the winter, however a recent surge in ice growth has occurred during a period of high pressure over the centre of the continent, resulting in a slowing of the circumpolar winds, giving rise to warmer conditions for the continental ice sheet areas and colder conditions in surrounding seas, allowing ice to grow extensively there.

In contrast to the Antarctic, sea ice in the Arctic has seen dramatic losses in recent years.

Sea ice is an important factor in climate because it reflects the sun's energy back into space. Losses in the Arctic are seen as concerning because less reflective cover means more solar energy is absorbed by the dark ocean. This raises temperatures which, in turn, melts, even more, sea ice, creating a feedback loop.

A graph shows the extent of Antarctica's sea ice extent in recent years against the 40-year average.